Evaluation of the utility of the ISTH-BAT in haemophilia carriers: a multinational study

IntroductionThere has been increasing recognition in recent years that female carriers of haemophilia manifest abnormal bleeding; however, data on the use of bleeding assessment tools in this population are lacking. AimOur objective was to validate the ISTH-BAT in haemophilia carriers to describe bleeding symptoms and allow for comparisons with factor levels and other patient groups. MethodsThis was a prospective, observational, cross-sectional study performed by members of Global Emerging HEmostasis Panel(GEHEP). Unselected consecutive haemophilia carriers were recruited and a CRF and the ISTH-BAT were completed by study personnel. ResultsA total of 168 haemophilia carriers were enrolled: 155 haemophilia A and 13 haemophilia B. The mean age was 40years (range: 20-82). Carriers had higher mean bleeding scores (BS) compared with age-matched controls (n=46; 5.7 vs. 1.43; P<0.0001) and Type 3 VWD OC (n=32; 3.0; P=0.009), but lower BS compared with women with Type 1 VWD (n=83; 8.7; P<0.0001). Fifteen carriers reported haemarthrosis, and of those six had normal FVIII/FIX levels. There was a significant but weak negative correlation between BS and factor level (Spearman's r(2)=-0.36, P<0.001). ConclusionOur results show that haemophilia carriers experience abnormal bleeding, including haemarthrosis. Overall, BS in women with Type 1 VWD>haemophilia carriers>Type 3 VWD OC>controls. Understanding the performance of the ISTH-BAT in this population is a critical step in future research aimed at investigating the underlying pathophysiology of abnormal bleeding, with the ultimate goal of optimizing treatment.